The size of the circle represents the degree of correlation, with a higher correlation indicated by a relatively larger circle. The higher the height of the rod (the distance from 0), the higher the correlation degree (a positive number represents a positive correlation, and a negative number represents a negative correlation). The circle color represents the P value obtained via the statistical method to determine the correlation. In this study, a Pearson correlation coefficient greater than 0.3 and with P < 0.05 was considered a positive correlation, and a Pearson correlation coefficient less than - 0.3 with P < 0.05 was considered a negative correlation
